A prior art roller nip cleaning apparatus is described, for example, in JP 55-91515 (A). In this arrangement, the ink and washing fluid received in the nip is conveyed out of the nip via a roller rotating at different roller speeds and is scraped off by means of a stripping device.
Nips which are filled with a fluid, such as varnish, are also known, for example, from DE 3,225,564 C2.
DD-WP 263,264 A1 discloses a varnishing unit which possesses a blowing device arranged over the entire roller width and preferably directed onto the nip. This device serves for evaporating water from the varnish in order to increase the viscosity.
DE 3,220,537 A1 discloses a solution which dampens the roller surfaces by means of fluid feeds and which prevents ink or varnish from drying on during a press standstill or print cut-off. When a relatively large amount of fluid is fed, the fluid is returned into a collecting vessel.
It is known, furthermore, to clean roller nips manually. However, this is very complicated and subjective influences cannot be avoided.
A disadvantage of the solutions mentioned is that the nip receiving the fluid cannot be cleaned completely, since some residual fluid always remains in the nip and therefore cannot be prevented from drying on. In rollers which can be moved away from one another, there is the disadvantage of soiling the machine, since, when the roller is moved away, the residual fluid can flow out over the width of the nip. This is counteracted by carefully moving the rollers apart from one another and simultaneously sucking up the fluid with a cloth. However, this constitutes an impractical handling of the cleaning process.